Plummer plus dogs = a pretty fun road movie

★★¼5 Rated R. 104 minutes.

“Boundaries” opens with a conversation between a woman and her offcamera shrink. But the real therapy doesn’t kick in until the patient, a divorced, gardenvariety neurotic named Laura (played with an appealing mix of spunk and brokenness by Vera Farmiga), embarks on that staple of Hollywood renewal: the road trip.

In the case of this lively if at times labored dramedy by writerdirector Shana Feste (“Endless Love”), Laura’s journey to inner peace — found somewhere between Portland, Ore., and Los Angeles — is undertaken in the company of her estranged father, Jack (Christopher Plummer), and her teenage son, Henry (Lewis MacDougall).

The former is a potdealing ne’erdowell who’s just been kicked out of his retirement community (but whose claim to be dying is belied by the twinkle in his eye). The latter is a skinny misfit, given to drawing graphic nude portraits of adults that he describes as pictures of their “soul.” That gift has gotten him expelled from his school.

It’s a familiar formula: Cram a group of amusingly troubled characters together in a car — here they’re also accompanied by a menagerie of adorable foster dogs that have been taken in by Laura — and, over the course of several pit stops, they will work out whatever issues they have.

Chiefly, those involve abandonment. Jack was never there for Laura or her sister (Kristen Schaal), an L.A. dogwalker and free spirit who has agreed to take in the old man. As for Henry, he still harbors resentment of his father, who left the family years ago.

Needless to say, the itinerary will feature a brief sojourn at the home of the deadbeat dad (Bobby Cannavale), conveniently located in the pretty Bay Area town of Sausalito. Other picturesque way stations include the Big Sur estate of one of Grandpa’s wealthy customers (Peter Fonda), a Buddhist monastery and the home of a hippie art forger (Christopher Lloyd).

Along the way, reconciliation and closure ensue.

If it all sounds a bit pat, it is. The metaphor of the stray dog no one wants is uncomfortably onthenose. And yet the unimpeachable cast makes the best of Feste’s narrative contrivances, not to mention her proclivity for obvious humor: “I need to change my diaper,” Jack keeps repeating — because that’s where he’s hidden his marijuana.

Like the effects of Grandpa’s weed, the film’s performances loosen up — and at times even find the profundity in — a stiff and sometimes silly tale.